Enhancing Pointer Network for Sentence Ordering with Pairwise Ordering Predictions

  • Yongjing Yin Xiamen University
  • Fandong Meng Tencent Inc
  • Jinsong Su Xiamen University
  • Yubin Ge University of Illinois at Urbana-Champaign
  • Lingeng Song Tencent AI Lab
  • Jie Zhou Tencent Inc
  • Jiebo Luo University of Rochester

Abstract

Dominant sentence ordering models use a pointer network decoder to generate ordering sequences in a left-to-right fashion. However, such a decoder only exploits the noisy left-side encoded context, which is insufficient to ensure correct sentence ordering. To address this deficiency, we propose to enhance the pointer network decoder by using two pairwise ordering prediction modules: The FUTURE module predicts the relative orientations of other unordered sentences with respect to the candidate sentence, and the HISTORY module measures the local coherence between several (e.g., 2) previously ordered sentences and the candidate sentence, without the influence of noisy left-side context. Using the pointer mechanism, we then incorporate this dynamically generated information into the decoder as a supplement to the left-side context for better predictions. On several commonly-used datasets, our model significantly outperforms other baselines, achieving the state-of-the-art performance. Further analyses verify that pairwise ordering predictions indeed provide extra useful context as expected, leading to better sentence ordering. We also evaluate our sentence ordering models on a downstream task, multi-document summarization, and the summaries reordered by our model achieve the best coherence scores. Our code is available at https://github.com/DeepLearnXMU/Pairwise.git.

Published
2020-04-03
Section
AAAI Technical Track: Natural Language Processing